DESCRIPTION: Round gobies are similar in appearance to native sculpin and tubenose goby. Adult round gobies are 10 to 25 cm in length and have mottled gray, olive green, and brown markings (parental males are black). Their dorsal fin may appear greenish in color and it lacks spines. A black spot is usually present on the front dorsal fin, yet, some gobies from Lake Erie lack this identifying characteristic. They have raised eyes, fused pelvic fins that form suction disk (unlike native sculpin), and grow to a length of up to 17.8 cm in US waters. Round gobies grow larger in their native European range. In this species, the males guard the nest of eggs and newly hatched young. Round gobies will feed nocturnally. They appear to detect prey only while stationary. Round gobies prefer rock, sand, cobble, gravel, and macrophyte habitats and hide in crevices. In their native range they generally inhabit near shore areas, but will migrate during the winter months to depths of up to 50 m. Round gobies can tolerate a wide range of temperatures and oxygen concentrations between 0.3 and 0.9 ml/L. They can inhabit slightly brackish waters and are able to survive under conditions of degraded water quality.

PATHWAYS/HISTORY: Round gobies are native to the Caspian and Black Sea regions, including their tributaries. They have been introduced to the Great Lakes region of North America, probably in ballast water discharged by transatlantic ships originating from Eastern Europe. The round goby was first found in North America in 1990 in the St. Clair River.

RISKS/IMPACTS: This benthic fish species has the potential to seriously impact North American aquatic ecosystems. Researchers are studying its biology, distribution, and management - as well as working to predict its potential ecological, recreational, and economic impacts. Populations of native sculpin and logperch have exhibited a substantial decline in the St. Clair River where gobies were first introduced. Round gobies prey on darters, sculpins, logperch, and other small fish. They are known to ingest eggs/fry of lake trout and eggs of lake sturgeon. Round gobies may become a nuisance to anglers by removing bait from hooks, or because anglers catch gobies instead of sport fish. They also may interfere with habitat restoration projects. Round gobies are aggressive toward other fish and may drive native fish away from prime spawning areas. They out-compete native fish for food due partially to an ability to feed in darkness and to the presence of a suctorial disk located on their pelvic fin which allows them to attach to rocks/substrates and remain fixed on the bottom even in faster currents (tubenose and round gobies are the only fish to possess this unique characteristic). On the positive side, round gobies will eat zebra mussels, however substantial impacts upon zebra mussel populations is unlikely. They are also a food source for larger predatory fishes and water snakes.

MANAGEMENT: Control Measures include the use of electrical barriers and piscicides to deter movement. Prohibiting transport of round goby for use as live bait may limit spread.

WHAT YOU CAN DO: Learning to identify round gobies and educating yourself on their ecological and economical impacts is a start to help stop their spread. You can also help by practicing a few good techniques for stopping the spread of any aquatic nuisance species. Never empty your bait bucket into a different body of water from where you obtained your bait. Dispose of unused bait in the trash rather than in the water. If you find a round goby in waters different from what they are already known to be in contact your state Department of Natural Resources.

PROFILE CREDIT: Dani Crosier and Dan Malloy - IMAGE CREDIT: David Jude